In AVC (Advanced Video Coding) that is an image coding technique, a concept of a hypothetical reference decoder (HRD) is introduced so as to transmit streams without failure (refer, for example, to Non-Patent Document 1). An encoder needs to generate bit streams with the rate controlled so as not to cause failure in a hypothetical decoder.
Various methods are proposed as the method for rate control (refer, for example, to Patent Document 1 and Patent Document 2).